From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] libata: automatically use DMADIR if drive/bridge requires it Date: Fri, 22 Feb 2008 11:32:21 -0500 Message-ID: <47BEF915.1020106@pobox.com> References: <47B9D64C.3000705@rtr.ca> <47B9F05A.1060207@rtr.ca> <47BC6100.9020906@pobox.com> <47BC7727.1090508@rtr.ca> <47BCFD4E.4070100@gmail.com> <47BE9F66.5040404@tw.ibm.com> <47BECF0E.5040809@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:34825 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759981AbYBVQc3 (ORCPT ); Fri, 22 Feb 2008 11:32:29 -0500 In-Reply-To: <47BECF0E.5040809@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: albertl@mail.com, Tejun Heo , IDE/ATA development list , Alan Cox , Ricardo Salveti de Araujo Mark Lord wrote: > Albert Lee wrote: >> Tejun Heo wrote: >>> Back in 2.6.17-rc2, a libata module parameter was added for >>> atapi_dmadir. >>> >>> That's nice, but most SATA devices which need it will tell us about it >>> in their IDENTIFY PACKET response, as bit-15 of word-62 of the >>> returned data (as per ATA7, ATA8 specifications). >>> >>> So for those which specify it, we should automatically use the DMADIR >>> bit. >>> Otherwise, disc writing will fail by default on many SATA-ATAPI drives. >>> >>> This patch adds ATA_DFLAG_DMADIR and make ata_dev_configure() set it >>> if atapi_dmadir is set or identify data indicates DMADIR is necessary. >>> atapi_xlat() is converted to check ATA_DFLAG_DMADIR before setting >>> DMADIR. >>> >>> Original patch is from Mark Lord. >>> >>> Signed-off-by: Tejun Heo >>> Cc: Mark Lord >>> --- >>> I don't have a bridge which sets DMADIR but so only checked atapi_dmadir >>> parameter. Thanks. >>> >> >> The patch looks good. However, it seems there is no realworld IDE-to-SATA >> bridge that requires DMADIR and also mangles IDENTIFY PACKET bit-15 of >> word-62 to indicate its presence. >> >>> From the previous test of the IDE-to-SATA bridges, only the Sil 3611 >> requires the host software to hint on ATAPI DMADIR. But Sil 3611 doesn't >> mangle IDENTIFY PACKET word-62: >> http://www.spinics.net/lists/linux-ide/msg01514.html > .. > > Ahh, great! We have "history" here! > > But there are more SATA bridges out there than the ones Alber has there > (SiI 3611/3811, Marvell 88i8030/88SA8040, Acard ARC770, JMicron JM20330). > > There's the Marvell 88SA8050, and I have a funky looking thing here > that says "SataLink SPiF223A" on it (????). I wonder what it does? > And how many other ones are there? > > The Word62 patch (from Tejun) is simple enough that the "complexity" > point from before really doesn't hold water. I'm going to apply Tejun's patch. It's fine (as I noted I conditionally ACK'd your original patch). My opinion, though, it that this is merely coding to the spec, rather than making a bunch of real-world hardware work. All the SATA<->PATA bridges I have, that support ATAPI, do not flag DMADIR. Jeff